Updated Bullet firing functions

-Updated Bullet firing functions to handle Vector2f instead of a double
for x pos and a double for y pos
-Updated GameManager and PhysicsManager code to use the new functions
Removed SetPosition in Bullet

-This function has been implemented in GamePiece ( base class of all
objects ) using Vector2f and is now not needed in other classes.
Made xDir and yDir into a singel Vector2f

-Changed TCPMessage to use Vector2f for direction instead of two double
-Updated MessageSender and GameManager according to this change